diff --git a/rexml.gemspec b/rexml.gemspec
index 620a8981..d7fb506f 100644
--- a/rexml.gemspec
+++ b/rexml.gemspec
@@ -55,6 +55,8 @@ Gem::Specification.new do |spec|
   spec.bindir        = "exe"
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
 
+  spec.required_ruby_version = '>= 2.6.0'
+
   spec.add_development_dependency "bundler"
   spec.add_development_dependency "rake"
   spec.add_development_dependency "test-unit"